Over a billion people in the world smoke or otherwise use tobacco products such as cigarettes, cigars, chewing tobacco, and snuff. These tobacco products generally contain tobacco-specific nitrosamines (TSNAs), which are typically formed during curing and/or processing of tobacco leaves. Since TSNAs have been linked to a variety of cancers in animals and humans, including oral, lung, esophageal, and pancreatic cancers, it would be desirable to reduce or eliminate TSNAs in tobacco products.
Although various treatments of tobacco plants and/or harvested tobacco leaves have been suggested to reduce TSNA levels, the suggested treatments are often associated with significant drawbacks. For example, one proposed treatment, which involves extracting a TSNA with a 0.1 N KOH solution, can introduce toxic compounds into tobacco. Another method for reducing TSNAs, which is described in U.S. Patent Publication No. 2016/0029689, involves heating tobacco material to a temperature of greater than 100° C. in the presence of a liquid or steam to release at least a portion of a TSNA from the tobacco material. While this method may be capable of partially reducing the amount of a TSNA in tobacco material, the method is cumbersome and can lead to extraction of water-soluble nicotine and unwanted reduction of its levels in the tobacco material. Further, TSNAs and other toxicants evaporated into the vapor phase can create an environmental hazard and require costly disposal measures.
Some of the suggested methods for reducing nitrosamine levels are particularly unsuitable for tobacco products containing nicotine. For example, U.S. Pat No. 3,317,607discloses the reduction of nitrosamines by treatment with a metal and an acid to form corresponding disubstituted hydrazines. Not only does the utilization of toxic metals render the disclosed method unsuitable for nitrosamine reduction in products intended for consumer use in general, but the disclosed method is particularly unsuitable for nicotine-containing tobacco products since the nicotine can form highly toxic complexes with the metals—such nicotine-metal complexes can be used as insecticides and fungicides and are inappropriate for consumer tobacco products.
Accordingly, improved methods for reducing TSNAs are needed.